A pediatrician is a doctor for babies, children, and teenagers — not for adults, except when the patient is still in that doctor's care.

A pediatrician is指的是 a doctor for babies, children, and teenagers專門看嬰兒、兒童和青少年的醫生 — not for adults不看成人, except when the patient is still in that doctor's care除非病人本來就一直是這位醫生在照顧的。

This is the American spelling. The British spelling is paediatrician, with an extra a after the p. Same doctor, same job; the letters follow American vs British habits, like pediatric / paediatric.

This is the American spelling這是美式拼法。The British spelling is paediatrician英式拼法是paediatrician, with an extra a after the p在p後面多了一個a。Same doctor, same job是同一種醫生、同一種工作; the letters follow American vs British habits拼法只是跟著美式或英式的習慣走, like pediatric / paediatric就像pediatric／paediatric一樣。

In a hospital they work in pediatrics. Parents take a sick child to the pediatrician for checks, shots, fevers, and growing-up problems. The word is normal and respectful in American English.

In a hospital在醫院裡 they work in pediatrics他們是在pediatrics（小兒科）工作。Parents take a sick child to the pediatrician父母會帶生病的孩子去看pediatrician for checks, shots, fevers, and growing-up problems做檢查、打針、看發燒，或處理成長過程中的問題。The word is normal and respectful in American English這個字在美式英文裡是正常又帶著尊重的說法。

Though actually, you do not say 'a pediatric' for the person. That form is an adjective and wants a noun: pediatric care, a pediatric ward.

Though actually不過其實, you do not say你不會說 'a pediatric' for the person「a pediatric」來稱呼這個人。That form is an adjective and wants a noun那個形式是形容詞，需要後面接名詞: pediatric carepediatric care（小兒照護）, a pediatric warda pediatric ward（小兒科病房）。